The effect of placing drains and no drains after caesarean section in obese patients on patients' post‐operative wound complications: A meta‐analysis

Abstract The purpose of this research is to investigate the influence of placement of drainage channels and non‐drainage channels in obese women on post‐caesarean delivery. Documents were retrieved from four databases, such as PubMed and Embase. This study was not limited in time, language, or geography. This trial was conducted using either a cohort or a randomized, controlled study to compare the efficacy of placement of drain in caesarean delivery channel in obese women with or without drain for post‐operative wound complications. The study excluded those who were restricted to those who were not overweight. The main results were the wound infection, the bleeding of the wound and the dehiscence. The risk of bias was evaluated by two authors with a risk‐of‐bias tool for nonrandomized intervention trials. The meta‐analyses only included those that were considered to have a low‐to‐medium risk of bias. The data were pooled with a random‐effects model to determine the relative risk and 95% confidence interval (CI). The quality of the evidence in the selection of results was evaluated. Of 329 related trials, eight were eligible for inclusion. There were 1868 cases of obesity who received C‐section. Among them, there were 451 cases of drain and 1417 cases of non‐drain. No statistical significance was found in the rate of post‐operation infection of the post‐operation between non‐drain or drain treatment of obesity patients (OR, 0.8; 95% CI: 0.48–1.33; p = 0.39). Compared with those with non‐drain, there was a reduction in the risk of haematoma after drain (OR, 0.34; 95% CI: 0.20–0.58; p < 0.0001). The results showed that there were no significant differences in the influence of drainage and non‐drainage on the post‐operative dehiscence of the patients with obesity (OR, 0.84; 95% CI: 0.15–4.70; p = 0.85). The results showed that there were no statistically different effects on the rate of post‐operation wound infection and dehiscence after operation, but the rate of haematoma during drain operation was lower.


Key Messages
• This meta-analysis assessed the effect of placing drains versus no drains after caesarean section in obese women on patients' post-operative wound complications.• Drainage versus no drain during caesarean section in obese patients did not significantly differ in terms of post-operation infection and wound dehiscence.• Intraoperative drainage during caesarean section in obese patients reduces the risk of post-operative haematoma in patients.

| INTRODUCTION
In the United States, the prevalence of obesity is so high that over 50% of Americans are classed as overweight or obese.The growth is mainly seen in the 30-to-39-year-old population, particularly female.Since 2007, about 25% of US females have been identified as overweight and have a body mass index (BMI) of 30 kg/m2 . 1,28][9] For each BMI rise of 5 units, Tran et al. pointed out that there was an almost twofold increase in the risk of wound infection. 10The prevalence of wound complication was further aggravated by the prevalence of GDM. 11aesarean section (CS) is a widely used surgery in modern obstetrics.Nevertheless, the surgical methods and the operative phases do differ considerably. 12Such differences are dependent on many factors, such as the preference of the surgeon, the features of the patient and the facilities and environment that are available. 13The most frequent complications of CS are superficial surgery areas, including sepsis and bleeding. 14The risk of WC is also increased by the presence of diabetes.
A popular, but controversial, technique in CS is the insertion of subcutaneous drainage of the wound.The benefit of this method is that it can draw out any potentially generated blood or plasma within the skin, which can result in post-operation pain or provide a rich base for microorganisms to grow and infect. 15Thus, it was hypothesized that a drainage would reduce the burden of surgical site infection.However, the use of subcutaneous drains has become highly controversial among some surgeons.
Complications after surgery may include surface infection, dehiscence or fluid in the area of the injury.The following signs occur in 3%-5% of caesarean sections, which frequently lead to long hospital stays and administration of antibiotics, thus causing higher post-partum cares. 16,17Skin infections are a component of surgical site infections (SSIs) in surgery and the Centers for Disease Control (CDC) says SSIs are infections which develop for up to 30 days after surgery.9][20][21] This research is aimed at identifying the influential factors of post-operation wound healing in obese women.

| Search strategy
For the meta-analyses, a complete and systemic search strategy was developed to make sure that all related studies were included.Research was conducted through multiple scientific databases, such as PubMed, Cochrane Library and Embase.Various combinations of particular keyword are employed to facilitate an exhaustive investigation of the field.Table 1.The review covers all relevant articles published prior to October 2023.Literature published in English was the focus of the search.Headings and summaries are reviewed for their relevance to the subject, followed by careful evaluation of all possible related papers that are eligible for meta-analyses.

| Selection criteria
This meta-analysis had a clear set of inclusion and exclusion criteria for the selection of studies.

| Exclusion criteria
The exclusion criteria were (1) studies for which full text was not available and (2) studies presented as conference papers, abstracts, case reports and other documents.
The initial screening process consisted of a review of the titles and abstracts of the identified articles, followed by full-text assessment of those who met the initial criteria.
Any discrepancies said to have arisen during the study selection process would be resolved through discussion and consensus (Figure 1).

| Data extraction
The data were extracted in a standardized format, and the collection of data from the chosen trials was performed by two independent evaluators.The collected data contained the identity of the study, including the author and the date of the publication.Data on the design of the study, for example, sample size, were also documented.Concrete interventions and comparisons have been carried out, including with regard to drainage.It also extracted the results and the risk of bias evaluation and evaluated their quality with instruments like the Cochrane Recommendation for Risk Bias Evaluation Tool.Differences among the reviewers were settled by discussing or consulting with a third reviewer.

| Statistical analyses
The meta-analyses were carried out by specialized software, such as RevMan 5.3, and the results were computed with mean difference and 95% confidence interval (CI), while binary outcomes were evaluated by odds ratio (OR) with 95% CI.The difference between the two trials was assessed by the p-statistical method, where I 2 was higher than 50%, which suggested that there was a large degree of heterogeneity, and therefore a random-effects model was employed.A sensitivity analysis was conducted to evaluate the reliability of the results, and a funnel graph and Egger regression test were used to identify possible publishing bias.A sub-group analysis was conducted where necessary.The results showed that all the statistics were two-sided with p values below 0.05.

| Study characteristics
Among 329 papers on obesity, we selected eight publications to be included in the final analysis.Eight studies had publication dates between 2000 and 2021.There were 1868 cases of obesity who received C-section.Among them, there were 451 cases of drain and 1417 cases of non-drain.The sample size was between 24 and 591.The profile of obesity in C-section patients is presented in Table 2.The evaluation of the quality of this trial is presented in Figures 2 and 3.

| Wound infection
In seven studies, the incidence of wound infection following caesarean section in obese patients was reported.Drainage group was 327, and non-drainage was 1273.No statistical significance was found in the incidence of postoperative wound infections in the Caesarean section of obese subjects between drain and non-drain (OR, 0.8; 95% CI: 0.48-1.33;p = 0.39) (Figure 4).

| Haematoma
Five studies have demonstrated the risk of bleeding from a wound following a Caesarean section in an obese person.Among them, 380 had been drained in the course of the operation and 365 had not been drained.The results indicated that the incidence of post-operative bleeding after caesarean delivery was lower among those with obesity in drain (OR, 0.34; 95% CI: 0.20-0.58;p < 0.0001) (Figure 5).

| Wound dehiscence
Two trials have shown the risk of wound dehiscence following caesarean section in obese patients.Of those, 148 had been drained in the course of the operation, while 170 had not been drained.There was no significant difference between operative drainage and non-drainage for post-operation dehiscence in obese women with caesarean section (OR, 0.84; 95% CI: 0.15-4.70;p = 0.85) (Figure 6).

| Publication bias
The publication bias of the study was determined by means of a funnel diagram of the wound infection and the wound haematoma following Caesarean section (Figures 7 and 8).

| DISCUSSION
1][32] Doctors point out that the incidence of wound injury among nonobese women who have had an operation on their abdomen is 4%, versus 29% among those who are overweight.Since we all need to perform surgery on overweight people, it is very important to cut down on the prevalence of obesity.Although there has been great progress in surgery during the last two decades, there is a debate about how to apply drainage into the subcutaneous space.Supporters believe that preventive drainage can help to minimize post-surgical infections by decreasing fluid build-up, which is a beneficial environment for bacteria to grow.Opponents say that drainage tubes allow bacteria to migrate into the wound, which raises infection rates. 33s the incidence of caesarean birth continues to increase, proper surgery is critical to prevent caesarean delivery.
While the preventive placement of drainage systems to prevent wound complications is controversial, the results of their efficacy in this setting have found inconsistent results. 20n the current meta-analyses of 329 cases involving obesity, we selected eight publications to be included in the final analysis.Eight studies were published between 2000 and 2021.There were 1868 cases of obesity who received C-section.Among them, there were 451 cases of drain and 1417 cases of non-drain.The sample size was between 24 and 591.The results showed that there were no statistically different effects on the rate of postoperation wound infection and dehiscence after use drainage tube, but the rate of haematoma after operation was lower.
What is strong about this research is that we can look at the impact of broad demographic and operative factors on the post-operative recovery of the patient, with the help of a comprehensive routine collection of data.
Therefore, the findings of the study have implications for the application of various operative methods in clinical practice.
While we acknowledge that there are some limitations to this study, we believe that we have a limited sample size and analysis due to the scope of the study, the scope of the data and its quality.In the majority of trials, the percentage of missing data was comparatively small.Comparatively few trials, as well as wide variation in outcomes, are major constraints.The majority of our analysis was done in English, which could also have been a limiting factor.Moreover, most research on C-section involves a retrospective study which does not contain the  clinical indications for surgery or certain co-morbidities like diabetes.Furthermore, the heterogeneous nature of the research is also one of the limits of our research.

| CONCLUSION
In this study, we found that there was no discrepancy in the risk of post-operative wound infection and wound dehiscence, but there was a significant decrease in post-operative haematoma in drain group.Thus, there is a need for a prospective multi-centre, large, randomized, controlled study of Caesarean section in obese women.

F I G U R E 3
Summary of risk of bias.F I G U R E 4 Forest plot of the effect of drainage versus non-drainage during caesarean section in obese patients on the patient's postoperative wound infection status.CI, confidence interval.F I G U R E 5 Forest plot of effect of drainage versus non-drainage during caesarean section in obese patients on patients' post-operative wound haematoma status.CI, confidence interval.

F I G U R E 6
Forest plot of the effect of drainage versus non-drainage during caesarean section in obese patients on the patients' postoperative wound dehiscence condition.CI, confidence interval.F I G U R E 7 Funnel plot of the results of drainage versus nondrainage during caesarean section in obese patients on the patients' post-operative wound infection status.OR, odds ratio.

F I G U R E 8
Funnel plot of the results of drainage versus nondrainage during caesarean section in obese patients on patients' post-operative wound haematoma status.OR, odds ratio.